Alcoholic fermentation / by Arthur Harden.

  • Arthur Harden
Date:
1932
Catalogue details

Licence: In copyright

Credit: Alcoholic fermentation / by Arthur Harden. Source: Wellcome Collection.

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    only sweet liquors could be fermented (“ Ubi notandum, nihil fer- mentare quod non sit dulce,” Becher, 1682), and finally Cavendish [1766] determined the proportion of fixed air obtainable from sugar by fermentation and found it to be 57 per cent. It gradually became recognised that fermentation might yield either spirituous or acid liquors, whilst putrefaction was thought to be an action of the same kind as fermentation, differing mainly in the character of the products (Becher). As regards the nature of the process very confused ideas at first prevailed, but in the time of the phlogistic chemists a definite theory of fermentation was proposed, first by Willis (1659) and afterwards by Stahl [1697], the fundamental idea of which survived the overthrow of the phlogistic system by Lavoisier and formed the foundation of the views of Liebig. To explain the spontaneous origin of fermentation and its propagation from one liquid to another, they supposed that the process consisted in a violent internal motion of the particles of the fermenting substance, set up by an aqueous liquid, whereby the combination of the essential constituents of this material was loosened and new particles formed, some of which were thrust out of the liquid (the carbon dioxide) and others retained in it (the alcohol). Stahl specifically states that a body in such a state of internal disquietude can very readily communicate the disturbance to another, which is itself at rest but is capable of undergoing a similar change, so that a putrefying or fermenting liquid can set another liquid in putrefaction or fermentation. Taking account of the gradual accumulation of fact and theory we find at the time of Lavoisier, from which the modern aspect of the problem dates, that Stahl’s theoretical views were generally accepted. Alcoholic fermentation was known to require the presence of sugar and was thought to lead to the production of carbon dioxide, acetic acid, and alcohol. The composition of organic compounds was at that time not under- stood, and it was Lavoisier who established the fact that they consisted of carbon, hydrogen, and oxygen, and who made systematic analyses of the substances concerned in fermentation (1784-1789). Lavoisier [1789] applied the results of these analyses to the study of alcoholic fermentation, and by employing the principle which he regarded as the foundation of experimental chemistry, “ that there is the same quantity of matter before and after the operation,” he drew up an equation be- tween the quantities of carbon, hydrogen, and oxygen in the original sugar and in the resulting substances, alcohol, carbon dioxide, and
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